Method and apparatus for filling and capping an acoustic ink printhead

Abstract

The invention is directed to a method and apparatus utilizing a capping element having a sealing element or gasket which is pushed against the orifice plate of an acoustic ink printhead when capping and filling. This traps a small volume of air around an array of orifices in the orifice plate which prevents ink from exiting the orifices while the printhead is being filled with ink.

Having thus described the invention, we hereby claim:  
     
       1. A method for filling an acoustic ink printhead with ink at a capping and filling station comprising at least one capping element having a chamber defined therein and a sealing element disposed around a periphery of the chamber, the method comprising steps of: 
       aligning the printhead with the capping element;  
       moving the sealing element of the capping element into engagement with the printhead such that the sealing element touches the printhead but transmits substantially no force on the printhead;  
       exerting a force on the sealing element to seal the chamber such that the force is transmitted to the printhead through the sealing element and to generate an air cushion within the chamber thereby facilitating establishing the ink flow;  
       establishing ink flow in the printhead;  
       removing the force on the capping element to remove the force on the printhead; and,  
       moving the sealing element out of engagement with the printhead.  
     
     
       2. The method as set forth in  claim 1  wherein the air cushion per nozzle is less than 7.5×10 −5  inch 3 /psi (volume per filling pressure above threshold). 
     
     
       3. The method as set forth in  claim 1 , wherein exerting the force on the sealing element comprises further moving the capping element in the vertical direction such that the force is transmitted through the sealing element from spring mechanisms disposed within the capping element. 
     
     
       4. The method as set forth in  claim 1  wherein the vent valve is closed after moving the sealing element into engagement with the printhead and opened after ink flow is established. 
     
     
       5. A method for filling an acoustic ink printhead with ink at a capping and filling station comprising at least one capping element having a chamber defined therein and a sealing element disposed around a periphery of the chamber, the method comprising steps of: 
       aligning the printhead with the capping element;  
       driving a belt connecting a drive motor to a cam shaft that is connected to the capping element such that the cam shaft rotates and moves the capping element in a vertical direction  
       moving the sealing element of the capping element into engagement with the printhead such that the sealing element touches the printhead but transmits substantially no force on the printhead;  
       exerting a force on the sealing element to seal the chamber such that the force is transmitted to the printhead through the sealing element;  
       establishing ink flow in the printhead;  
       removing the force on the capping element to remove the force on the printhead; and,  
       moving the sealing element out of engagement with the printhead.  
     
     
       6. The method as set forth in  claim 5  wherein removing the force and moving the sealing element out of engagement comprises further rotating the cam shaft such that the capping element moves in an opposite vertical direction. 
     
     
       7. A method for filling an acoustic ink printhead with ink at a capping and filling station comprising at least one capping element having a chamber defined therein, a vent valve positioned in the chamber, and a sealing element disposed around a periphery of the chamber, the method comprising steps of: 
       aligning the printhead with the capping element;  
       moving the sealing element of the capping element into engagement with the printhead such that the sealing element touches the printhead but transmits substantially no force on the printhead;  
       exerting a force on the sealing element to seal the chamber such that the force is transmitted to the printhead through the sealing element;  
       establishing ink flow in the printhead;  
       removing the force on the capping element to remove the force on the printhead;  
       moving the sealing element out of engagement with the printhead; and,  
       selectively opening and closing the vent valve positioned in the chamber.  
     
     
       8. A method for filling an acoustic ink printhead with ink at a capping and filling station comprising at least one capping element having a chamber defined therein and a sealing element disposed around a periphery of the chamber, the method comprising steps of: 
       aligning the printhead with the capping element;  
       rotating a lever connected to a cam shaft that is connected to the capping element such that the cam shaft rotates and moves the capping element in a vertical direction;  
       moving the sealing element of the capping element into engagement with the printhead such that the sealing element touches the printhead but transmits substantially no force on the printhead;  
       exerting a force on the sealing element to seal the chamber such that the force is transmitted to the printhead through the sealing element;  
       establishing ink flow in the printhead;  
       removing the force on the capping element to remove the force on the printhead; and,  
       moving the sealing element out of engagement with the printhead.  
     
     
       9. A capping and filling apparatus useful in connection with printheads employed in acoustic ink printers, the apparatus comprising: 
       a plurality of capping elements, each capping element comprising  
       a first body portion having a chamber defined therein, a valve disposed in the chamber and a shoulder portion positioned on a periphery of the chamber,  
       a sealing element positioned on the shoulder,  
       a second body portion upon which the first body portion is gimbal mounted, and  
       a third body portion comprising a first shaft within a second hollow shaft extending from the second body portion;  
       a base element having a plurality of shaft apertures defined therein and a corresponding plurality of collar elements circumferentially extending from the apertures and sized to receive the third body portions; and,  
       a drive mechanism operatively engaged to the third body portions.  
     
     
       10. The apparatus as set forth in  claim 9  wherein the first body portions are resiliently mounted on the second body portions through spring mechanisms. 
     
     
       11. The apparatus as set forth in  claim 10  wherein the drive mechanism is a motor that is operatively engaged to the third body portions through a drive belt that engages a rotatable cam shaft attached to the base element that connects to the third body portion. 
     
     
       12. The apparatus as set forth in  claim 11  wherein the drive motor drives the drive belt to rotate the cam shaft to move the third body portions in a vertical direction such that, when the printheads are aligned with the capping elements, the sealing elements are brought into contact with the printheads and forces are selectively exerted on the printheads by the spring mechanisms through the sealing elements. 
     
     
       13. The apparatus as set forth in  claim 12  wherein the valves are opened or closed by the cam shaft rotating to move the valve vertically. 
     
     
       14. The apparatus as set forth in  claim 13  wherein a flow of ink is established in the printheads when the forces are exerted and the valves are closed. 
     
     
       15. The apparatus as set forth in  claim 9  wherein the valve comprises a wiping blade. 
     
     
       16. An apparatus for use with an acoustic ink printhead comprising: 
       at least one capping element aligned with the printhead, the capping element having a chamber defined therein, a valve positioned in the chamber, and a sealing element disposed around a periphery of the chamber;  
       means for moving the sealing element of the capping element into engagement with the printhead such that the sealing element touches the printhead but transmits substantially no force on the printhead;  
       means for closing the valve;  
       means for exerting a force on the sealing element to seal the chamber such that the force is transmitted to the printhead through the sealing element;  
       means for opening the valve;  
       means for removing the force on the capping element to remove the force on the printhead; and,  
       means for moving the sealing element out of engagement with the printhead.  
     
     
       17. The apparatus as set forth in  claim 16  wherein the means for moving the sealing element and for opening and closing the valve comprises a belt connecting a drive motor to a cam shaft that is connected to the capping element such that the drive motor drives the belt and the cam shaft rotates and moves the capping element in a vertical direction. 
     
     
       18. The apparatus as set forth in  claim 17  wherein the means for exerting the force on the sealing element comprises spring mechanisms disposed within the capping element. 
     
     
       19. The apparatus as set forth in  claim 16  wherein an air cushion is generated within the chamber by the exerting means thereby facilitating establishing the ink flow. 
     
     
       20. The apparatus as set forth in  claim 16  wherein the valve opens in a direction toward the printhead. 
     
     
       21. The apparatus as set forth in  claim 16  wherein the means for moving the sealing element comprises a lever rotatably connected to a cam shaft that is connected to the capping element such that the cam shaft rotates and moves the capping element in a vertical direction.